Or, more specifically, with microbes — the tiny bacteria and viruses that can make us sick but can also be helpful as well. And we have billions, if not trillions of them blanketing our skin. We know a lot how easily these “bad” bugs can jump from person to person, or transfer via a doorknob or handrail — that’s the basic mode of transportation for flu and cold viruses, after all. But can “good” bugs be just as facile at making these transfers? And what impact can these back-and-forths have on our health?

Curious about that question, Jessica Green, director of the Biology and Built Environment Center at the University of Oregon, decided to study the creatures that reside on our skin. And what better way to analyze how readily they pass from one person to another than through a contact sport? Green, it turns out, is a three-year veteran of the Emerald City Roller Girls, a Eugene, Ore., roller derby league. With firsthand experience of the amount of physical contact that team members have with each other, Green figured roller derby athletes would make an ideal test population for tracking the microbes that make their home on skin.

Green and her team tested the entire team’s skin microbiome — the sum total of all the microbes living on each skater’s skin — by sequencing the bugs they obtained from the forearms of team members, both before and after an hour-long bout. Reporting in the journal PeerJ, she and her colleagues found that, remarkably, members of the same teams tended to have similar compositions of bacteria on their skin before the match. That could be the result of their close physical contact with each other, but could also reflect things such as their common environment, which could lead to similar skin composition (moist or dry, for example) that attracts similar microbial strains.

Less remarkably, they also documented that these bugs do a lot of mixing and matching as their hosts make physical contact. Before an hour-long match, each team had a distinct group microbiome skin profile; after the session it was impossible to tell who was on which team by their microbes alone. “Our data suggests that touching people plays a big role, which is not that shocking a finding,” says Green.

But that documentation could have implications for understanding how transmissible microbes are even if there isn’t intimate contact. “Humans shed a certain number of bacteria per hour, and also kick up bacteria wherever we walk. We’re constantly walking around in an airborne microbial soup, or microbial aura,” says Green. Understanding what impact that cloud may have on our health could open up new ways of thinking about preventing or treating disease. A recent paper, for example, described a strain of beneficial bacteria living in skin pores that tends to combat the acne breakouts that are the bane of adolescence; some people are genetically blessed with this strain, while others are not, but the latter could take advantage of treatments that repopulate their skin with the pimple-fighting bugs.

Researchers are just starting to peer into this invisible world of tiny residents that live in and within us, and are coming to appreciate that these microbes may have a larger hand in our health than we could have imaged. Some studies have linked the bugs in our gut, for example, to our risk of obesity, while other strains that line our nasal and respiratory tract can play a role in our tendency toward asthma and allergies. Some early work even connects certain populations of bacteria to a greater risk of developing some types of cancer.

Green is eager to pursue the connection between skin microbes and health by studying people in small enclosed spaces, such as conference rooms, to better understand how the microbial aura may be harnessed to better help, and not harm, our health. So the next time you shake hands with someone, or take an airplane flight, think about the invisible exchange of microbes that’s likely occurring. And don’t be so afraid. It could be a good thing.